Process of treating animal pelts



Patented Aug. 13, 194: 2,211,645

UNITED STATES PATENT OFFICE 2,211,645 PROCESS OF TREATING ANIMAL PELTS Jose B. Calva, Minneapolis, .Minn.

No Drawing. Application June 14, 1940, Serial No. 340,567

'1 Claims. (Cl. 149-28) This invention relates to the treatment of permanence, since it merely formed an outer covfilamentous materials particularly the fur, hair ering on the filaments, an incomplete layer in or wool of animal pelts to encase such filamentous most cases, and in many instances the leathery portions of the pelt, with or without chemically portions of the pelt were deteriorated.

modifying the parent substance, permanently Various reactant substances may be used in 5 straighten or permanently curl the said filacarrying out the invention, and the following is ments, to impart gloss or finish thereto, or to' only one example of the application of the prinmake the filaments resistant to chemical or to ciples in the treatment of tanned pelage such as mechanical action. In the present invention that of the sheep, or other soft or hard fur, wool '10 the treatment of the filamentous parts of the or hair to straighten the wool or hair portions of pelt, namely'the fur, hair or wool, is carried the pelt and impart a high gloss to the hair, out under conditions such that the skin or fur or wool, and impart to it hydrophobic propleathery portions of the pelt are not deteriorated. erties, all without deterioration of the leather The treatment of the filamentous portions of parts of the pelt. The gloss of the hair, fur or the animal skin or pelt may be carried out in wool is a function of the straightening. Bril- 15 various ways, as by the formation of condensaliance, or 8 i n usually in le when tion products with the parent substance of the super-curling fur, because of the change in light filaments with properly selected re-agentsj The reflecting prop brought out y e p yschemical mechanism is analogous to that of ical structure produced.

synthetic resin formation, but in this manner E I I 20 of proceeding, the active chemical functional azamp 6 groups of the parent substance of the filaments Preliminary treatment and formation of the of the skin or pelt act as one of the condensation protective coating and impregnation of the leathre-agents, while the other is supplied according er parts of the skin or pelt:

to requirements, for producing the desired effect, The tanned and dried pelt is optionally first 25 result or reaction, without materially destroying degreased either by washing or by treatment with the physical structure of the filaments themahydrocarbon solvent such as petroleum, or benselves. In the case of hair or wool, the pelt is zol, or ethers, or chlorine-substituted hydrocartreated with a substance which chemically rebons, or with any suitable degreasing or washing acts with the fibre substances of such filaments agent, after which the pelt may or may not be 30 including the keratin or amino-bearing material dried. The pelt is then soaked in water which of the filament, to form therewith in situ a completely penetrates the leather and serves as permanent synthetic resin or resinoid, or cona vehicle to draw thereinto, uniformly and graddensation products, or the like. In carrying out ually a properly selected substance which will the treatment of the fur, hair or' wool, of the penetrate the fibrous structure of the leather, 35 pelt, the leathery portions are coated or impregand so coat it as to prevent deleterious contact nated with non-injurious protecting agents therewith of re-agents subsequently applied. As which are later either removed or allowed to rean example of such a substance is a water solumain in the leathery portions of the pelt, as detion of corn syrup, of a concentration of from 40 sired. 50 to 85%. The preliminary treatment with 40 The inventionisapplicable for the treatment of water is customary in tanneries to insure the tanned pelage such for example as that of sheep uniform penetration of the dressing or softening to permanently straighten the wool and give gloss agents, whether the skin has been dehaired or not. and finish, all without deterioration of the leather In my process, the excess water is removed and parts of the pelt, so that the treated pelt can be then the pelt is thoroughly covered on the side used for making fur garments in imitation of opposite to that of the hair or wool, with a proother more expensive furs. tective impregnant and coating such as a water Straightening of the hair, fur or wool parts of mixture of an inert or non-reactant material such the pelt has heretofore been attempted but has as above mentioned.

not proved to be permanent, the wool again be- After impregnation of the leather by this procoming curly or kinky after wetting. Previously tective impregnating and coating solution the pelt to the present invention, efforts were made mereis thoroughly dried. The drying is desirable for 1y to coat the fibres with greases, waxes or soaps two reasons: First, because if the leather is imin an attempt to straighten them and keep them pregnated with moisture it will selectively withstraightened, but such coating material had no draw from the reacting mixture, the most hygro- 55 scopic constituents, such as mineral acids, to result in destruction of the leather; and second, because it is undesirable, for accuracy to introduce into the impregnating solution any more water than the calculations require. This application of a water solution of corn syrup or other protective agent has for its object the formation of a continuous film on the surface of the leather, as well as within the fibrous structure thereof, to prevent deleterious action of the reagent or re-agents subsequently used. In other words, this application is protective of the leather portions of the skin or pelt. Corn syrup is preferred because of its cheapness and easy availability, but other substances such as glycol-boriborate or glyceryl-boriborate or similar watersoluble film-forming materials can be used. If desired the protecting of the leather may be done by impregnating and coating the leather of the pelt with any other suitable protecting agent.

Example II Treatment of the fur, hair or wool portions of the pelt or skin after formation of the protective impregnation and coating on the leather parts of the pelt.

After the tanned pelt is prepared as above, it is treated with a reactant which is prepared as follows: To 60 parts by weight of commercial cresol is added 40 parts of an azeotropic mixture composed of benzol, alcohol and water. The above is saturated with enough hydrogen chloride to give the proper acidity, which may range from 0.1 to 0.4 normal.

Other mineral acids or acid producing substances possessing condensing properties can also be used instead of hydrogen chloride. As an example there may be mentioned sulphuric acid and mixtures of anhydrous aluminum chloride and hydrochloric acid.

As an example there may be used 60 parts of cresol, 8 parts of denatured ethyl alcohol; 40 parts of benzol and 4 parts of concentrated hydrochloric acid. The acid concentration should be carefully balanced, because if too high will destroy the azeotropic mixture, and if too low will slow down the reaction during subsequent treatment of the wool. The hydrochloric or other acid is used as a catalyst and dehydrating agent and may be added in any suitable manner, such as by bubbling hydrogen chloride through the mixture. The above mixture or solution is brought to a temperature approximately within the range of 30 to 55 0., and the previously prepared pelt is submerged in this solution for from 15 to 300 minutes. In the case of sheep pelts treatment at 38 C.ffor 120 minutes gives good results. During this period the skin may be moved to insure good and uniform contact of the reacting substances with the wool. At the end of the time period the skin is removed from the bath and the excess of treating solution is removed mechanically as by squeezing or centrifuging or by washing with benzol, or other suitable solvent. Some of the impregnating liquid penetrates the fibres themselves and some is only retained by capillary attraction. The latter being undesirable for this process, it is removed, if for no other reason than to avoid waste. After removal of the excess solution the skin is submerged for from 5 to 30 minutes in a solution of commercial formaldehyde having a concentration of about 40% byvolume and having a temperature of between about 30 to 60 C. For sheep skin a treatment at 45 C. for 20 minutes gives good results.

Atrhigher temperatures and at a given concentration of reactants, a shorter time of treatment is necessary. It is desirable to bring about the desired changes in the minimum of time, with some of the amino groups which by now have.

been rendered active by the hydrochloric acid in the impregnating solution, can be easily made to react with formaldehyde to give rise to the well known condensation products between amines and aldehydes.- Furthermore, the formaldehyde under these circumstances reacts with some of the excess of cresol which is adsorbed by the fibre, giving rise to Bakelite-like products.

Similar results can be obtained by carrying out the same reaction at ordinary temperature and pressure for 24 to 72 hours, removing the fibrous materials from the formaldehyde solution and drying them at a temperature of about C. The fibrous materials are then washed to free them of any water soluble substances and dried again.

Of the reacting substances which I have described, cresol in Example II is very useful. However, cresol has only a limited solubility in water but is completely miscible in hydrocarbons and alcohol. On the other hand hydrochloric acid, whose presence is also necessary for the reaction is only slightly soluble in hydrocarbons and in cresol, but is very soluble in water. Therefore, in order to make a homogeneous mixture of hydrochloric acid, hydrocarbon and cresol it is desirable to use a fourth substance termed a homogenizer, which in this instance is alcohol. Be-

tween alcohol, benzol, and water a constant boil-' ing point azeotropic mixture is formed which will dissolve hydrochloric acid gas in sufiicient amount for the purposes of this invention without suffering a disturbance of equilibrium. However,

if the maximum tolerance of this azeotropic mixture for hydrochloric acid gas is exceeded the homogeneity of the mixture is destroyed and it separates into two layers, one composed mainly of hydrochloric acid and water and alcohol, and the other of benzol and alcohol.

The principal object in the preparation of this solution is to have a physically homogeneous mixture, the presence of water and other reactants which are water-non-miscible bothbeing required. For the proper mixing of these non-miscible substances the homogieniaer is important. It is therefore necessary to have a liquid capable of dissolving both the 'catalyzer and the reactants.

To straighten the wool or hair'of pelts or skins, it is preferable to carry out the reaction in the presence of an acid catalyst. Thus in Example II the wool portions of the pelt are reacted with a hydroxy-aromatic compound, such as cresol, in

the presence of hydrochloric or sulphuric acid.

A fine fur like a beaver will not tolerate as high a temperature as a sheep skin, partly because of the thickness of the skin.

The results of the above treatment will be a A straightening or the fur, hair or wool portion 01' till till

til)

the pelt, with a simultaneous gloss (rbr straightening).

Example III Removal of excess reactants and finishing of the skin or pelt:

The skin or pelt treated as in Example II is removed from the treating solution and is washed in running cold water and is then put to soak for a time in a solution containing about onefourth pound of common salt per gallon with an equal amount of sodium bicarbonate. The running cold water is for the purpose of removing as much as is possible 01 theiormaldehyde. During the treatment with formaldehyde the protection given to the leather with the proper inert material is nullified because these inert materials are soluble in the formaldehyde solution. Where any other protective agent is used, it is removed by any suitable means. The next operation, which is washing, has for its object the removal (as completely as possible) of all entrained substances, which were used during impregnation and during formaldehyde treatment, as well as the complete removal of the inert substance that was used in production or high protecting the leather. Incomplete removal of the above mentioned substances would lead to a severe weakening, if not complete destruction, of the leather during the subsequent heat treatment or combing. The function of salt in this salting solu= tion is to suppress the swelling of the leather, which swelling annuls the effects of tanning. The sodium bicarbonate is used to supply enough potential alkali (without being over-alkaline) to neutralize any hydrochloric acid which might have been retained or adsorbed by leather or fibrous material. After the above soaking which is for the purpose of removing the last traces of acid, the skin is washed with water. This wash= ing is for the purpose of freeing the skin from any salt which has penetrated it from the previous solution and which has been formed at the expense of hydrochloric acid and sodium bicarbonate on the inside of the skin. The general object is to rid the skin of sodium chloride. The skin is then dried and then prepared to be mechanically finished by combing, during which operation the temperature of the wool should be between 70 to 110 C. This heat treatment completes the formation of the resinous or resinoid condensation products which it is the object to produce. The combing operation thus carried out onthe dry and chemically modified fibre assists 7 in completing the condensation reactions which had been taking place at lower temperatures.

Example IV Treatment of the fur, hair or wool portions oi tanned pelage such as skins or pelts which have been "tanned by oil tanning or formaldehyde tanning is as follows:

The tanned pelt is first degreased and then treated with an agent for protecting the leather portions of the pelt, all as described in Example I. The hair, fur or wool portions of the skin or pelt are then subjected to the action or formaldehyde or formaldehyde producing substances such as hexamethylenetetramine preferably aided by a mild alkaline catalyst such as-triethanolamine and operating in an autoclave under pressure preferably at a temperature corresponding to a developed pressure between 20 and '75 pounds. The time of treatment is 30 to 90 minutes. The resulting fur, hair or wool possessesgloss and is silky and free of kinks. The thus treated skin or pelt is removed from the autoclave and is washed thoroughly with water as set forth in Example III and may then be dried and heated if desired. Heating will increase polymerization oi the formaldehyde treated iur, hair or wool 01 the pelt which results in some stifiening action. This is an economical way of treating wool pelts and has the advantage that the final product is completely free from odor. In addition the treatment has the eflect of rendering the keratinous portions of the fur, hair or wool less susceptible to chemical reaction, when brought in contact with strong alkalies or acids.

Example V It the wool portion or the pelt is treated with a suitable re-agent, at the proper temperature,

in an alkaline medium, for example, acetyl chloride in pyridine, or even glacial acetic acid in pyridine the result will be a wool whose curl has been substantially increased (super curl). In this case, the amino groups of the keratinous material of fibre are acetylated. In such reactions the leather portions of the pelt are, of course, protected by the use of a suitable coating and impregnating agent as set forth in Example I.

The following is an example of the procedure for the formation of the condensation products, around, or to encase, an animal fibre, as distinguished from the utilization of the keratins of the fibre in the formation of such condensation products.

Example Vi The filamentous material after degreasing by any suitable means, and after treating the leather portions of the pelt with a protective agent, as previously described in Example I, is coated with iurfuryl alcohol as for example by dipping. The excess furiuryl alcohol is then allowed to drain off, and the alcohol coated fur, hair or wool is then either exposed to hydrogen chloride or dipped in a solution of hydrechloric acid oi any concentration from 5 to 37%. By this process the furfuryl alcohol is transformed into a resinous substance formed in situ, which encases and adheres to the fibre. There is no reaction in this case, between thematerial of the fibre, and the furfuryl alcohol or hydrochloric acid, and the protective agent in the leather prevents the reaotants from damaging the leather portion of the pelt.

L'airzmple Vii In the following process for treating animal fibres, the parent substance oi the fur, hair or wool fibres reacts with the re-agents, giving rise to a resinoid substance. In this case the skin or pelt is preliminarily treated as in Example I so as to protect the leather portions of the skin or pelt, and is then either coated or, by allowing sumcient time, the hair or wool is impreg mated with an aqueous solution of saligenin. The coated or impregnated fibres are then subjected to the action of gaseous ammonia, or are dipped in a water solution of ammonia. The fibres thus treated are dried, and will be found to be either coated without penetration, or its structure will be penetrated by the resinous body, resulting from the reaction. This penetration is to be distinguished from coating without penetration which latter isalso a feature of the present invention. Saligenin requires the presence of an alkaline environment in order to be con-- verted into a resinoid. Such an environment 7 of the fibres, or by the action of ammonia without reaction with the parent substance of the 'fibre. 'I'he time required for penetration varies with the type of hair, fur or wool fibre of the pelt but can be accomplished within a period of about 72 hours. It is possible, by varying the time, to control the degree of penetration, or entirely to prevent penetration and simply coat the filament.

Furthermore, one of the re-agents usediin the formation of saligenin is formaldehyde, and this substance is present in excess or in equilibrium with phenol, in the saligenin reaction products. These two substances, phenol and formaldehyde also react with keratins giving rise to resinous substances, but are prevented from injuring the.

leather portion of the skin or pelt by the presence of the initially applied protective agent.

The above example also'includes the general type in which the fibre is coated by a resinoid formed in situ. Internally it has in its structure resinoid bodies, formed from saligenin, and keratin, the two having reacted to form the resinous substance.

In Example VI, a mineral acid, namely hydrochloric acid was the catalytic agent for the reaction of resinification. In Example VII, a base, namely ammonia was the catalytic agent inducing a similar type of reaction.

In carrying out the present invention, the available reactive groups of the substances comprising the parent material being treated are utilized as starting materials in the formation of resinoid materials. The types of reactions involved depend upon the substance being treated,

that is to say, whether it is fur, wool, hair or bristle and may be illustrated by the following examples vofresinoid formation: (1) condensation of aromatic amines, with aldehydes; (2) condensation of amides and aldehydes; (3) condensation of amino groups linked to carbonyl groups with aldehydes; (4) condensation of amines with hydroxy-aromatic compounds; (5) condensation of aldehydes with hydroxy-aromatic compounds; (6) condensation of amino acids with aldehydes; (7) condensation of proteinic substances with aldehydes; (8) condensation of proteinic substances with hydroxy-aromatic compounds; (9) condensation of aldehydes among themselves; and (10) condensation and polymerization of unsaturated compounds.

In the case'where a chemical change of the parent substance of the fibrous material takes place, the change is obtained without destroying the filamentous structure, or form, and thus it is possible to impart to the filaments those desirable properties needed for their intendeduses. For instance, in the case of furs, the wool of sheep skin can be converted into a filamentous product hardly distinguishable, by the naked eye, from hair. The invention is applicable for curling as well as straightening, and curling can be carried to a point wherein the final product has a compact felted structure. The fur, hair or wool treatment processes impart to these filaments either stiifness or softness as desired making them resistant to the action of depoly- 2,211,645 may, be furnished by the keratinous substance product or products in the filament, straightening or curling of the filament is induced, depending upon the reacting medium selected to form the condensation product. The invention is not intended to be limited to the character of the synthetic resin or condensation product which is formed and which changes the character of the filament. In the case of hair or the like, the chemical structure of the keratinous, aminobearing filamentous material of the fur, hair or wool portions of the skin or pelt is changed.

It is to be understood that, by the practice of theinvention herein described .the parent substance of the fibre, animal, can be made to in situ react in various degrees with the treating reeagent, or the resinoid substance can be formed in situ without any reaction involving utilization of the substance of the fibre. In some instances there are surface reactions; in some no surface reactions; in some there is a deeper reaction amounting to impenetration and in some the reaction may involve any selected portion of the filament.

In using the expression in situ it is the intention to distinguish from the separate making of a resinoid substance and dissolving it by suitable means and then applying it to the fibres, and then subsequently eliminating or removing the solvent by physical or chemical means; as for example, by dissolving a material or synthetic resin in a solvent which is later eliminated by evaporation, or by dissolving this resin or resinoid substance which'reacts with that chemical whose reaction product is later broken up by use of a third reagent such for example as rosin soap, precipitated subsequently with an acid producing substance.

This application is a continuation-in-part of my application Serial Number 106,427 filed October 19, 1936.

Obvious variations may be made in the processes herein described without departing from the spirit of the invention claimed.

I claim as my invention:

1. A process of treating fur pelts to modify the fur by resinification of the fur in situ with a resinification agent which is normally capable of deteriorating the leather of the pelts, which comprises forming a protective coating on such leather portions and then treating the fur by reaction with such resinification agent.

2. A process of treating fur pelts to modify the fur by resinification of the fur in situ with a resinification agent which is normally capable of deteriorating the leather of the pelts, which comprises impregnating the leather portions of the pelt with a substance capable of protecting said leather portions from deterioration by the resinification agent and then treating the fur with said resinification agent.

3. The art of processing filamentous covering of the skin of animals which consists in treating 'the back of a tanned pelt with a water solution of corn syrup, then treating the filaments with a reactant composed of a solvent, 2. hydroxy-aromatic-compound and an acid, then removing ex cess reactant and treating with an aldehyde, then washing in cold water, and then treating with a solution of sodium chloride and sodium bicarbonate.

4. The art of processing filamentous covering of the skin of animals which consists in protecting the tanned pelt with a chemically inert substance, then treating the filaments with a reactant composed of a solvent, a hydroxy-aromatic com- 74 pound and a catalyst, then removing excess reactant and treating with formaldehyde, then washing in cold water, and then treating with a solution of sodium chloride and sodium bicarbonate.

5. The art of processing filamentous covering of the skin of animals which consists in treating the back of a tanned and degreased pelt with a water solution of corn syrup, then treating the filaments with a reactant composed of a solvent, cresol and an acid catalyst, said reactant being at a temperature of 35 to 55 C., and the treatment being continued for from 15 to 300 minutes, then removing excess reactant and treating with formaldehyde, having a concentration of about 40% by volume and at a temperature of about 30 to 60 C. for about 5 to 30 minutes, then washing in cold water, then treating with a solution of sodium chloride and sodium bicarbonate for onehalf to thr e hours, then washing, and then drymg and echoing the filaments with simultaneous application of heat to the fibres being combed to make them reach a temperature of from 60 to 115 C.

6. A process of treating fur pelts to modify the fur by resinification of the fur in situ with a resinification agent containing an aldehyde, which is normally capable of deteriorating the leather of the pelts, which comprises forming a protective coating on such leather portions, and then treating the fur by reaction with such resinification agent.

7. A process of treating fur pelts to modify the fur by condensation of the fur in situ with a condensation agent which is normally capable of deteriorating the leather of the pelts, which comprises forming a protective coating on such leather portions and then treating the fur by reaction with such condensation agent.

JOSE B. CALVA. 

